Tropical Storm Nadine likely to form this week

A tropical system in the Atlantic has a 90 percent chance of becoming Tropical Storm Nadine in the next 48 hours.

A tropical system in the Atlantic has a 90 percent chance of becoming Tropical Storm Nadine in the next 48 hours. (National Hurricane Center)

Scott Dance, The Baltimore Sun

As Hurricane Michael and Tropical Storm Leslie churn in the Atlantic with only limited impact on land expected, a new storm system is moving toward North America in the middle of the ocean.

The system, about 850 miles west of Africa's Cape Verde Islands, has a 90 percent likelihood of becoming a tropical cyclone in the next 48 hours. That would make it the 14th named storm of the season, to be dubbed Nadine.

It's too early to predict where the storm could be headed. It's currently moving west-northwestward at 15 to 20 mph.

Leslie and Michael are both headed northward, with Leslie making a brush with eastern Canada on Tuesday.

We are nearing the tail end of what is typically the heart of the hurricane season, so a slowdown in tropical activity could be occurring. El Nino is expected to set in this month as well, bringing wind shear that makes it difficult for tropical storms to strengthen.

NOAA's updated hurricane season forecast released in August called for 12-17 named storms, so there could be only a few left. NOAA predicted five to eight hurricanes, and there have been seven so far.

Only one, Michael, reached "major" hurricane status; NOAA predicted two to three major hurricanes.

Most forecasters refrain from estimating how many storms might make landfall in the U.S. There have only been four so far, with Isaac the most destructive.